Grinding machine

ABSTRACT

A grinding machine for conditioning the surfaces of steel slabs, billets, or the like to remove scale, exposed or hidden cracks and other surface irregularities. The entire grinding machine including the grinding wheel head and its supporting carriage travels on rails so that the grinding wheel may traverse the work. A rotary turret pivottally supports the boom housing for fore and aft rocking movements, and the grinding head is carried at the outer end of a relatively short boom which is fixed to and projects outwardly from the housing so that controlled angular movements of the turret will swing the grinding head and its associated grinding wheel over the surface of the work in order that the rotating grinding wheel may be shifted to an angular position wherein the grinding direction at the periphery of the wheel matches or nearly matches the longitudinal direction of any surface cracks which are undergoing spot eradication. The operator&#39;&#39;s control cab is positioned on the movable grinding machine carriage at a location where the grinding head is clearly and closely visible at all times.

United States Patent 1 Kaszuba [1 1 3,708,920 1451 Jan. 9, 1973 [75] Inventor:

[52] US. Cl. ..5ll32, 51/35, 51/47 [51] Int. Cl. ..B24b 7/02, B24b 27/04 [58] Field of Search ..5l/33 R, 47, 35, 32,178

[56] References Cited UNITED STATES PATENTS 2,364,879 12/1944 Talboys et al. ..5l/l78 3,052,067 9/1962 Dilks ..5l/35 3,245,176 4/1966 Muehlingm, ....Sl/33 R 3,253,368 5/1966 Vekovius ....51/33 R 2,769,280 11/1956 Comstock ..5 H47 3,156,072 11/1964 Boehme ....5l/35 2,750,714 6/1956 Muehling .5 H32 3,562,959 2/1971 Dooley, .lr. ..5 H47 Primary Examiner-Donald G. Kelly Attorney-Norman H. Gerlach [57] ABSTRACT A grinding machine for conditioning the surfaces of steel slabs, billets, or the like to remove scale, exposed or hidden cracks and other surface irregularities. The entire grinding machine including the grinding wheel head and its supporting carriage travels on rails so that the grinding wheel may traverse the work. A rotary tu'rretpivottally supports the boom housing for fore and aft rocking movements, and the grinding head is carried at the outer end of a relatively short boom which is fixed to and projects outwardly from the housing so that controlled angular movements of the turret will swing the grinding head and its associated grinding wheel over the surface of the work in order that the rotating grinding wheel may be shifted to an angular position wherein the grinding direction'at the periphery of the wheel matches or nearly matches the longitudinal direction of any surface cracks which are undergoing spot eradication. The operators control cab is positioned on the movable grinding machine carriage at a location where the grinding head is clearly and closely visible at all times.

PATENTEU JAN 9 I973 SHEET 1 [IF 2 IN VE N TOR ROBERT J KASZUBA WEE M4 Ally.

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IN VE N TOR ROBERT J. KASZUBA Affy.

GRINDING MACHINE The present invention relates to a grinding machine for conditioning metal surfaces, as, for example, the surfaces of a steel slab, in order to remove scale, i.e., the usual decarburized surface layer, and reveal any cracks or seams which may be hidden by such layer, such conditioning taking place preliminary to removal of such cracks or seams by a spot-grinding operation if necessary.

In the treatment of slabs and particularly slabs of stainless alloy and carbon steels, it is desirable to remove the above-noted defects from slabs and billets before advancing them to the finishing stages of processingjlf such defects are not removed by grinding or otherwise, they take on a predominant aspect in the finished product. The usual grinding wheel traversing operations across the surface of a slab may remove the scale or decarburized layer adhering to such surface,

but such operations seldom will remove all localized defects such as cracks, seams, inclusions and the like, and after surface conditioning by grinding wheel traversing operations it is necessary individually to spot-grind these localized defects by returning the grinding wheel selectively to the vicinity thereof.

Heretofore, in connection with a grinding machine which is capable of traversing the work (steel slab) or of being traversed by the work during the grinding operation, the grinding wheel which is associated therewith possesses fixedorientation with respect to the direction of traverse, the orientation invariably being such that the grinding direction is at right angles to the direction of traverse or, in other words, is a transverse direction with respect to the longitudinal axis of the slab or billet undergoing grinding. Thus, when during normal grinding operations there is encountered an elongated crack or seam which extends at a wide angle with respect to the rotational plane of the grinding wheel, the periphery of the grinding wheel acts on the remote edges of such crack or seam and tends to chip such edge away, thu's widening the defect instead of eradicating it. For proper crack or seam eradication, it is well known that coincident grinding along the axis of a crack produces optimum results since there is no tendency for the crack to open up and the opposite edges of the crack are worn away evenly until the crack disappears. Thus, the operation of a conventional grinding machine is frequently augmented by subsequent hand operation or spotting wherein'an operator attends to i such cracks or seams as have been widened during normal machine grinding by hand-spotting these cracks with a small. portable grinder which can be directed to treat the cracks in a longitudinal grinding direction.

There has recently been developed a fully automatic grinding machine which endeavors to treat cracks which have been widened during normal grinding machine traversing operations by the provision of facilities whereby the operator may return the grinding wheel to any given localized region in the vicinity of a crack or other flaw in the work and then set the machine into a grinding wheel oscillating cycle where the rotating grinding wheel rocks back and forth about a horizontal axis which extends transversely of the billet or slab. Such a machine forms the subject matter of U.S. Pat. No. 3,253,368, granted on May 31, 1966 and entitled SURFACE CONDITIONING GRINDING MACHINE. This type of crack treatment, although it obliterates the cracks, requires careful and detailed oscillation control involving considerable skill, and it is not altogether satisfactory in that, to remove any given crack, a wide swath or trough must be created to envelop the crack, thus removing more material than otherwise would be necessary. This is because, although the grinding wheel is capable. of oscillation about a horizontal axis, such axis at all times extends at a right angle to the direction of traverse. Additionally, to provide for such grinding wheel oscillation requires complicated oscillating mechanism including a special oscillating motor and a linkage arrangement whereby the grinding wheel boom may be caused to oscillate.

The present grinding machine is designed to overcome the above-noted limitations that are attendant upon the treatment of cracks during regular work traverse operations, or, if necessary, during subsequent spotting operations. Accordingly, the invention contemplates the provision of a grinding machine wherein the boom housing in its entirety is mounted on a rotatable turret or turntable, the latter being carried by the grinding machine carriage and capable of being rotated about a vertical axis during grinding operations and without necessitating lifting of the grinding wheel from the work. The grinding wheel boom which is associated with such boom housing is relatively short so that the swinging movements thereof incident to controlled rotation of the turret will not swing the grinding wheel on the outer end thereof off the edge of the slab or other work, even when the turret is rotated throughout an angle of in either direction away from the direction of traverse, i.e., the longitudinal axis of the billet or slab. In order to give the operator a close-up view of the work at all times, an operators control cab is mounted on the grinding machine carriage at a region which is close to the operating region of the grinding wheel, the cab moving bodily with the carriage and thus preserving its proximity to the grinding wheel at all times regardless of the region of the slab being operated upon.

Specifically, the present grinding machine is of the general type which is illustrated and described in aforementioned U.S. Pat. No. 3,253,368 in that it is similarly distinguished from a conventional swing-type grinding machine by utilizing a carriage which, in addition to. its traverse movements, is capable of moving'back and forth transversely of the work and'over such work, and in close proximity tothe upper surface thereof so that the machine can be operated with extremely low head room and possesses a low center of gravity. The present grinding machine adopts many of the advantageous features of the patented grinding machine such as the attaining of a close grouping of such operating points as are effective, first, to support the grinding wheel when it is not in contact with the work and, second, to afford such necessary reaction force to downward grinding pressure on the grinding wheel that effective wheel stabilization, both during the grinding operation and grinding wheel idling, will at all times be maintained. By reason of these features, high-speed grinding at relatively high pressures with a minimum of vibration is made possible regardless of whether normal traverse operations or subsequent spotting operations are in progress.

The grinding machine of the present invention is,

therefore, an improvement over the patented grinding machinev in that it superimposes thereon additional advantageous functions which effect a more satisfactory method of crack or seam treatment. As will become apparent when the nature of the invention is better un derstood, the basic structure of the patented grinding machine has been retained, as also have many of its functional operating characteristics, as, for example, the use of a supporting bridge structure for the boom carriage which slides on guide tubes which, in turn, are carried on movable front and rear main andtail stock carriages which straddle the work and travel in unison on rails. On the other hand, certain of the features of the patented grinding machine have been omitted from the present grinding machine since the utilization .of a turret, which enables the grinding wheel to'change its grinding direction as heretofore outlined, renders such features unnecessary. For example, with longitudinal crack or seamspotting made possible, grinding wheel oscillation as set forth above is no longer required. Still other features of the patented grinding machine have been omitted from the disclosure of the present machine inasmuch as they bear no direct relation to the rotating turret or its control mechanism. However, if desired, these featuresare readily capable of being ap plied to the present machine as disclosed.

The provision of a grinding machine such as has briefly been outlined above, and possessing the stated advantages, constitutes the principal object of the present invention. Numerous other objects and advantages, not at this time enumerated, will readily suggest themselves as the following description ensues.

4 The invention consists in the several novel features which are hereinafter described and are more particularly defined by the claims at the conclusion hereof.

In the accompanying two sheets of drawings forming a part of this specification, one illustrative embodiment of the invention is shown. I

In these drawings: 7

FIG. 1 is a front perspective view of a grinding machine embodying the principles of the present invention, the machine being illustrated as being in operation upon a steel slab; t

FIG. 2 is an enlarged sectional view taken substantially on the vertical plane indicated by the line 2--2 and in the direction of the arrows; I I

FIG. 3 is a combined electrical and hydraulic circuit diagram of the grinding machine control mechanism; and

FIG.4 is a front elevational view of a control panel which is employed in connection with the manual operation of the electrical instrumentalities of FIG. 3.

GRINDING MACHINE STRUCTURE IN GENERAL Referring now to the drawings in detail and in particular to FIG. l,.-an exemplary form of grinding machine for conditioning the surface of a steel slab or other similar piece of work having a horizontal planar upper surface is illustrated in its entirety and designated by the reference numeral 10. The disclosure of FIG. 1 issomewhat schematic in its representation inasmuch as certain instrumentalities such as the cabinet-enclosed electrical relays and similar devices, hydraulic piping, electrical lead wires, minor manual controls and adjusting mechanism, and other associated parts which bear no relation to the present invention have been omitted in the interests of clarity and are considered to fall within the scope of engineering.

development work during grinding machine production.

The grinding machine is shown in the drawings as being in operation upon the top or upwardly facing surface of a steel slab SL which is operatively supported on any suitable work support as exemplified by the wooden base structure 12. The latter may be erected in piecemeal fashion on the floor or other supporting surface of the establishment where the grinding machine is in use in order to accommodate the placement of the slab as to height, longitudinal and transverse span, etc. The supporting structure, although it may be erected separately at'the grinding region or area of the machine I0, may for descriptive purposes be regarded as a functional part of the machine.

The present grinding machine It] utilizes a single grinding wheel 14 which normally is designed for rotation about a horizontal axis extending parallelto the longitudinal axis or center line of the elongated slab SL or other piece of work to be operated upon. However,

according to'the present invention, and as will be made I clear subsequently, means are provided whereby the grinding wheel may be caused to deviate fromsuch parallel axis for crack or spot grinding operations when such operations are required. The grinding wheel 14 constitutes the operative grinding element of a more or less conventional grinding wheel head 16 which is carried at the forward or distal end of a relatively short boom 18, the boombeing carried on aboom housing 20 which is shown in the drawings as being in the form of a tiltable casting. The latter has a ledge portion 22 which constitutes a support for an electric grinding wheel drive motor M1.

The boom housing 20 is mounted for limited fore and aftrocking movement on a turret assembly 24 (see FIG. 2 as well as FIG. 1) which is supported for rotation about a vertical axis on a rectangular non-rotatableturret base 26, the latter beingsecured by bolts 28 to a main boom carriage 30 which is in the form of a relatively massive plate-like platform.'The turret assembly 24 comprises a rotatable turret body 32 which is, in the formof an inverted cup-shaped casting, the lower rim region of which is shaped to forman internal ring gear 34. The rotatable turret body 32 is centered on a fixed bearing support 36 of upright cup-shape design, such support being fixedly secured by bolts 38 to the turret base 26. A combined thrust and radial bearing 40 is effective between the rim region of the bearing support 36 and the turret body 32 to center the rotatable turret body on the fixed support 36. As shown in the drawings, said bearing 40 consists of inner and outer.

from the forward corner regions of the boom housing The aforementioned electric motor Ml which is carried on the ledge portion 22 of the boom housing operates through a multiple speed step-up transmission 54 to drive the grinding wheel 14, the transmission being connected to the grinding wheel by a belt and pulley arrangement 56 and having a gear ratio change handle 57 associated therewith. A multiple belt and pulley arrangement 58 serves to connect the motor M1 to the transmission 54. It is to be noted that the grinding wheel head 16 and its boom 18 are disposed on one side of the pivotal axis of rocking movement of the boom housing 20, while the electric motor M1 is disposed on the other side of such axis, the transmission 54 being positioned substantially directly above the said pivotal axis. The net result of this is that the grinding wheel head 16 and the motor M1 to a large extent counterbalance each other and lend a degree of stable equilibrium to the grinding wheel assembly as a whole. Since the boom 18 is extremely short, there is no appreciable framework deflection between the grinding wheel 14 and the pivotal axis of the boom 14. As will be described in greater detail presently when the operation of the grinding machine is set forth, the distance between the effective point of contact of the grinding wheel 14 on the slab SL and the vertical axis of rotation of the turret assembly 24 is sufficiently short that upon angular turning movement of the turret assembly 24 a wide arcuate sweeping movement of the grinding wheel over the surface of the slab SL may be attained whereby the grinding direction of the wheel may be shifted from its normal transverse direction across the slab, 90 in either direction to bring the grinding direction into parallelism with the axis of the slab. It

will be understood, of course, that the turret may be stopped in any intermediate position, in which case the direction of grinding of the grinding wheel 14 will extend at anangle to the longitudinal axis of the slab SL.

, Rotation of the turret body 32 is accomplished under the control of a reversible hydraulic turret motor M2 (see FIG. 2) which is secured by bolts 58a to the underneath side' of the fixed turret base 26 and seats within a recess 60 in said turret base. The motor M2 is provided with a motor shaft 62 which projects upwardly through an opening 64 in-the turret base 26 and carries a pinion 65. The latter as shown in FIG. 2 meshes with the ring gear 34. The motor M2 is of the rotary vane-type and, being reversible, it is provided with a pair of fluid ports 66 and 68 (see also FIG. 3) for the admission and expulsion of motive fluid to and from the. motor under the control of a directional valve DVl, the nature of which will be described subsequently when the hydraulic and electric circuit diagram of FIG. 3 is described in detail.

In order to impart tilting movements to the boom housing 20 as a whole and thus effect raising and lowering movement of the grinding wheel 14 from and to the slab SL or other piece of work being operated upon, as well as to supply the necessary grinding pressure of the grinding wheel to the work, an hydraulic motor in the form of an upwardly and forwardly inclined boom cylinder 70 has its lower end pivotally connected as indicated at 72 to the rear edge region of the upper supporting cradle 42. A plunger 74 projects upwardly from thecylinder 70 and has its upper end connected as at 76 to the rear edge of the boom housing 20. Operating fluid is selectively supplied to the cylinder 70 through lower and upper ports 78 and 80 (see FIG. 3) in order to tilt the boom housing 20 in opposite directions under the control of a second directional valve DV2 in a manner that also will be described in connection with the circuit diagram of FIG. 3.

The various grinding machine parts thus far described, i.e., the grinding wheel 14, the tiltable boom housing 20, the motor M1, the transmission 54, and the turret assembly 24 constitute an assembly of parts which will hereinafter be referred to as the boom and turret assembly, this assembly being mounted on and movable bodily with the aforementioned boom carriage 30. The latter is slidable in a forward and rearward direction on a pair of horizontally extending guide rods 82 which may be in the form of hollow guide tubes which overlie the slab-supporting base structure 12 and constitute a supporting bridge structure for the boom and turret assembly (20, M1, 54, 24). The front ends of the guide rails 82 are suitably supported on a tail stock carriage 84 which travels endwise and longitudinally on a single horizontally extending ground rail 86. The rear ends of the guide rails 82 are supported in the upper regions of a machine base assembly which is designated in its entirety by the reference numeral 88 and constitutes a main grinding machine carriage that travels on two ground rails 90 in unison with the tail stock carriage 84. Flexible accordion boots 91 surround the guide rods 82 in protective relationship and extend between the main boom carriage 30 and the machine base assembly 88.

The tail stock carriage 84 is-in the formof an inverted U-shaped frame having vertical supporting legs 92, the upper ends of which are connected by a horizontal beam 94. A back wall 95 projects across the framework of the tail stock carriage 84. The lower ends of the legs 92 carry dual-flanged traction wheels 96 which travel on the ground rail 86. The wheels 96 are power-driven under the control of individual reversible hydraulic motors M3 and M4 of the legs 92 and being operable in unison under the control of a directional valve DV3.

The main grinding machine carriage 88 is in the form of a wheeled vehicle and it constitutes a support for a large number of the grinding machine components, the nature of which will be described presently. Said main grinding machine carriage 88 includes a generally rectangular base frame 100 which is supported at its four corners by dual-flanged traction wheels l02, the pair of wheels at one end of the base frame 100 being driven by a common reversible hydraulic vane-type motor M5 and the pair of wheels at the other end of the base frame being driven by a similar common hydraulic motor M6. The four traction wheels 102 are adapted to travel in opposite directions on the ground rails 90.

' The previously mentioned grinding machine components which are carried. on the main grinding machine carriage 88 include two hydraulic pumps P1 and P2, together with a common electric motor M7. The pump Pl serves the various wheel motors M3, M4, M5 and M6 which are disposed in series relationship so that the four traction wheels 102 which control the reversible movements of the main grinding machine carriage 88 as well as the two traction wheels 96 which control the reversible movements of the tail stock carriage 84 are all six driven in unison and in the same grinding machine exclusive, of course, of the reversible hydraulic wheel motors M3, M4, M and M6 which are served by the pump P1. The hydraulic devices or units which are served by the pump P2 include the previously mentioned boom cylinder 70 and the reversible turret motor M2 as well as two additional hydraulic motors or cylinders 110 and 112, these latter cylinders serving to effect forward and rearward movement of the main boom carriage on the guide rods 82. The cylinders 110 and 112 have their opposite end region s suitably supported on the tail stock carriage 84 and the main grindingmachine carriage 88, respectively. A

piston 114 isslidably disposed in each of the cylinders 110 and l 12 and constitutes the reaction member of an endless cable loop which is established by means of a pair of cablesections 116 and l18,'the cable section 116 being secured to the piston 114 and passing outwardlythrough the forward end of the cylinder. Each cable section 116 passes around an idler pulley 120 and is anchored to a fixedly mounted reaction bracket 122 on a side edge of the main boom carriagev 30. Each cable section 118 similarly passes around an idler pulley 124 and is anchored to the associated bracket 122. As shown in' FIG. 3 conventional cable seals 126 are provided at the opposite ends of the two cylinders 110 and 112, such seals being of the lip seal type and serving to prevent egress of motive fluid fromthe cylinders 110 and 112 as the cable sections'slide through such seals into and out of the cylinders 110 and 112. Fluid ports 128 and 130 (see FIG. 3) are provided at the op posite ends of each of the cylinders 110 and 112 and are connected in parallel relationship, to the pump P2 by way of a directional valve DV4 (see also FIG. 3), as will-be described subsequently.

From the above description, it will be appreciated that when pressure fluid is supplied to the ports 128, the pistons ll4 will be driven or forced rearwardly in their respective cylinders, thus causing the cable sections 1l6and -l 18 to travel over their respective pulleys 120'and 124 in such directions as to apply tension to the cable sections 116 and thus .pull forwardlyv the brackets'122 and, consequently, the main boom carriage 30. When the pressure fluid is suppliedto the ports 130, the pistons 114 will move forwardly and place the cable sections 118 under such tension as to shift said carriage 30 rearwardly. g

' In addition to the principal functional grinding machine instrumentalities or parts thus far described, the grinding machine is possessed of certain advantageous design features which are associated with the boom carriage 30 and the main grinding machine carriage 88. These features include the the provision of a control panel cabinet 140 which is suitably mounted on and travels with said main grinding'machine within which there is housed a control panel (not shown) on which are mounted certain of the various electrical components which are associated with the machine. A

convenience and storage cabinet 142 for tools and other'loose equipment is mounted on and travels with the main grinding machine carriage 88. A series of steps 144 leadingto an elevated platform 146 affords 5 convenient access by the operator to a control cab 150 which is mounted on and travels with the main boom carriage 30. The cab .150 is provided with transparent protective and viewing windows152,one of which af-v fords the operator aiclose-up view of the grinding wheel 14 when it is in operation on the slab SL as well as affording a clear view of the upper surface of the slab so that spotting operations may be conducted with precision. A novel feature of the present invention consists in locating the operators cab 150 in a position where it is relatively close to the grinding wheel 14 and where it travels with the main boom carriage 30- to the end that regardless of the particular position of the grinding wheel along the longitudinal extent of the slab neither the'viewing angle nor the viewing distance of the operator from the working area of the machine is varied. An

additional advantageous feature of the present grinding machine resides in the provision of a dust shield 160 which projects'rearwardly from the back wall 95 of the tail stock carriage 84.

ELECTRIC ANDHYDRAUIJC CONTROL MECHANISM and P2; whereby the pump-Pl is caused to drive the various wheel motors M3, M4, M5 and M6 in unison in either direction for operating the traction wheels 96 and 102; whereby the pump P2 is caused selectively to operate the boom cylinder 70 and tilt the boom housing 42 bodily about the axis of the aligned or coaxial trunnions 52 for grinding wheel raising and lowering purposes; whereby said pump P2 actuates the cylinders 110 and 112 for boom carriage movements in forward and rearward directions; and whereby the pump P2 actuates the rotary hydraulic motor M2 to rotate the'turret assembly 24 in opposite directions, have not been illustrated in detail herein, the representation of such control means at various places in FIG.'1 being purely trated, the heavy lines represent hydraulic fluid lines or piping while the light lines represent circuit lead lines or conductor wires.

schematic. It is pointed out, however, that all control functions-are effected by the operator from the control 1 grinding machine operations'are schematically illus-- 9 (The Machine Carriage and Tail Stock Carriage Drive) Upon depression of a start button 180 which is associated with a conventional relay-actuated switch box 182, current is made available for all of the necessary electrical machine functions'and there is completed an electric circuit for energizing the motor M7 to drive the hydraulic pump P1 which, in turn, supplies fluid under pressure to the various reversible hydraulic wheel motors M3, M4, M and M6. This circuit extends from a current source S (which may be a commercial power line) through a pair of leads 11,13, the relay-operated contacts (not shown) of the start button 180, a lead 15, the motor M7, and a pair of leads 17, 19 back to the source S. Energization of the motor M7 serves to drive the pump P1 and also to establish a normal idling circuit extending from a reservoir or sump 184 through a line 186, the pump P1, a line 188, the directional valve DV3, and a line 190 back to the sump 184. A speed control valve SCV is disposed in the line 188 and serves a purpose that will be made clear presently.

Actually, the motors M3, M4, M5 and M6 have internal gear reduction facilities associated with them and directional control of these motors, all of which are disposed in series relationship, is effected under the control of the previously mentioned directional valve DV3, the solenoid of which is of the dual-acting type and has dual windings S1 and S2. Under normal idling conditions when the main grinding machine carriage 88 and the tailstock carriage 84 are motionless on their respective rails 90 and 86, both windings S1 and S2 of the valve DV3 remain deenergized and the previously described hydraulic circuit through the valve DV3 and the pump P1 obtains. However, if either solenoid winding of the directional valve DV3 is energized to the exclusion of the other, said valve will direct a flow of motive or pressure fluid through the series arranged motors M3, M4, M5 and M6 to set the various traction wheels 102 and 96 into motion in one direction or the other. If, for example, it isdesired to shift the carriages 84 and 88 to the right as viewed in FIG. 1, the solenoid S1 will be energized, thus establishing an hydraulic circuit extending from the sump 184, through the line 186, the pump P1, the line 188, the directional valve DV3, a line 192, the four serially arranged motors M3, M4, M5 and M6 a line 194, the directional valve DV3, and the-Iine190 back to the sump. For reverse rotation of the four wheel motors, a similar hydraulic circuit becomes effective upon energization of the solenoid winding S2 to the exclusion of the solenoid winding S1, the pressure fluid passing. through the four motors M3, M4, M5 and M6 in the opposite direction. The speed control valve SCV is provided for the purpose of regulating the traveling speed of the two carriages 84 and 88.

The two solenoid windings S1 and S2 of the directional valve DV3 are selectively energizeable by manipulation of the control handle 170 on the control panel 162 in the operators cab 150. Energization of the solenoid S1 iseffectived by shifting such handle 170 downwardly as illustrated in FIG. 4 or to the left as illustrated in FIG. 3, thus establishing an electric circuit from the source S, through the lead 11, a plurality of leads 23, 25, 27, 29, 31, 33, 35, 37, the solenoid winding S1, a lead 39, the No. 1 contacts (now closed) of a dual throw, dual contact switch assembly SW3 in associated relation with the control handle 170, a plurality of leads 41, 43, 45, 47 and the lead 19 back to the source S. Energization of the solenoid winding S2 of the directional valve DV3 is effected by shifting the handle 170 upwardly as illustrated in FIG. 4 or to the right as illustrated in FIG. 3, thus establishing a similar circuit through the winding S2, this circuit extending (The Boom Carriage Drive) Fore and aft movements of the main boom carriage 30 along the two guide rods 82 is effected under the control of the directional valve DV4. It will be remembered that at the time the electric motor M7 was initially energized, both pumps P1 and P2 were actuated by such motor, the pump P2 serving to supply pressure fluid selectively through the directional valve DV4 to the opposite ends of the cylinders and 112. Operation of the directional valve DV4 is effected under the control of the handle 164 on the control panel 162, downward movement of the handle serving to effect closing of the No. 1 contacts of a switch assembly SW4, and upward movement thereof serving to close the No. 2 contact of such switch assembly. The directional valve DV4 is identical to the directional valve DV3 and the dual contact switch assembly SW4 which is associated therewith is identical to the previously described switch assembly SW3/The hydraulic circuitryleading from the sump 184 through the pump P2 and the directional valve DV4 and extending to the ports 128 and at the opposite ends of the cylinders 110 and 112 and back to the sump is similar to the previously described hydraulic circuit extending from the sump 184 through the pump P1 and the directional valve DV3 to the motors M3, M4, M5 and M6 and back to the sump and, consequently, a detailed tracing of such hydraulic circuitry is not deemed to be necessary, it being sufficient to state that the pressure fluid flow to and from the ports 128 and 130 takes place through branch conduits or lines 181 and 183.

Similarly, the electrical circuitry for selectively energizing the solonoid windings S3 and S4 of the directional valve DV4 under the control of the No. 1 and No. 2 contacts of the'switch assembly SW4 remains substantially the same as that previously described in connection with the switch assembly SW3 and the directional necessary circuit through the solenoid winding S3 for shifting the directional valve DV4 to such position that pressure fluid is caused to enter the ports 128 of the cylinders 110 and 112 and drive the pistons 114 rearwardly as viewed in FIG. 1, thereby shifting the main boom carriage 30 forwardly on the guide rods 82 in the manner previously described. Similarly, reversal of the control handle 164 causes pressure fluid to enter the ports 130 of the cylinders 110 and 112 and drive the pistons 114 forwardly in order to effect rearward movement of the boom carriage.

(Boom Housing Tilting Operations) Tilting of the boom housing 20. in opposite directions to lower and raise the grindingwheel 14 into and of contact with the work is effected under the control of the directional valve DV2 and its associated switch assembly SW2, the latter'being controlled by the handle 166 on the control panel 162. The directional valve DV2 and the switch assembly SW2 are identical to the previously described directional valves and switch assemblies-andthe electrical and hydraulic circuitry which is associated therewith remains substantially the same and, therefore, requires no detailed description. It is deemed sufficient to point out that a'parallel arrangement of both electrical and hydraulic circuitry exists as between the directional valves DV2 and DV4, these two valves being connected to the common pump P2 by fluid lines 185 and 187 in the case of the directional valve DV4,and by fluid lines 189 and 199 in the case of the-switch assembly SW2 to close theNo. 1 and No. 2.

contacts thereof, each to the exclusion of the other.

(The Turret Drive) Rotation of the turret assembly 24 in opposite directions forvarying the angular disposition of the grinding wheel 14 and, consequently, the operative grinding direction as previously described is effected under the control of the handle 168 which is associated with'the switch assembly SW1. This switch assembly controls the selective energization of the solenoid windings S7 and S8 of the directional valve DV1, the latter valve being identical to the directional valves DV2, DV3 and DV4 and serving to control the pressure fluid flow from thepump P2 tothe turret motor In order to rotate the turret assembly 24 in a clockwise direction as viewed in FIG. 1, the operator will move the control handle 168 downwardly as viewed in FIG. 4 'or to the left as viewed in FIG. 3,.thus closing'the No. 1 contacts of the switch SW1 and establishing an electrical circuit extending from the source S, through leads 11, 23,. 25, 27, 29 and 31, a lead 55, the solenoid winding S7 of the valve DV1, a

lead 57, the No. 1 contacts of the switch SW1, a

sequence of leads 59, 61, 63, the leads 45, 47 and 19 back to the source; Energization'of the solenoid winding S7 shifts the directional valve DV1 so that pressure fluid flows from the sump 184, through the pump P2, the lines 185 and 189, a line 199, the directional valve DV1, a line 193, the boom motor M2, a line 200, the directional valve DV1 and a line 201 back to the sump. Such energization of the boom motor M2 serves to rotate the boom turret assembly 24 in a clockwise direction.Reverserotation of the boom motor M2 is effected by moving the control handle 168 so as to close the No. 2 contacts of the switch assembly SW1, thereby establishing a circuit through the solenoid winding S8 of the directional valve DV1, the circuit extending from the source S, through the leads 11, 23,25, 27, 29,

31, 33, a lead 65, the solenoid winding S8, a lead 67, the No. 2 contacts of the switch SW1, a lead 69, and

the leads 63, 45, 47 and 19 back to the source. Ener- I gization of the solenoid winding S8 shifts the directional valve DV1 so that fluid flows from the sump 184, through the pump P2, the lines 185, 189, 191, the directional valve DV1, the line 200, the boom motor M2, the line 193, the directional valve DV1, and a line 201 back to the sump.

GRINDING MACHINE OPERATION From the above description, it 'is believed that theoperation of the'grinding machine 10 will to a large extent be readily apparent without further description. Assuming a slab such as the slab SL to be positioned on the slab-supporting structure 12, depression of the start button 180 will set the motors M1 and M7 into operation', after which the operator may variously manipulate the control'handles 164, 166 and as required to effect the required boom carriage placement, 'boom housing inclination and main carriage travel respectively for conventional traverse operations of the grinding wheel back and forth along thelongitudinal extent of the slab SL, After the requirednumber of passes have been made and it is desired to spot grindlocalized regions of the slab in order to remove various forms of defects, these same control handles 164, 166 and 170 may be variously manipulated to bring the grinding wheel 14 to the proper location for such spot grinding operations, the plane of the grinding wheel remaining normal or at a right angle to the direction of traverse.

When an elongated crack or seam is encountered which requires grinding in a longitudinal direction as previously described, the operator may, by manipulating the control handle 168 to close either the No. l and No. 2 contacts of the switch SW1 each to the exclusion of the other, cause rotation of the turret assembly 24 in one direction or the other to bring the plane of the grinding wheel into coincidence with the vertical plane of the crack or seam, after which the control'handles 164, 166 and 170 may be variously manipulated so as to lower the grinding wheel into contact with the work at the vicinity of the crack or seam and to shift the main machine carriage 88 and the boom carriage 30 in such proportionate relationship that the'grinding wheel will follow the crack or seam line. It will be understood that the central-or medial positions of the various control handles are idle positions wherein neitherthe No. 1 nor the No.2 contacts which are respectivel'y associated with the switches, SW1, SW2, SW3 and SW4 are closed. .The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. Therefore, only insofarasthe invention hasv particularly been pointed out in the accompanying claims is the same to be limited.

Having thus described the invention what I claim as new and desire to secure by letters patent is:

1. In a machine for conditioning the upper surface of an elongated workpiece such as a slab, in combination, a work support for the workpiece, a main carriage, a pair of widely spaced overhead parallel guide rods mounted on said main carriage and completely overlying and extending ina fore and aft direction transversely of the work support, lying in a common horizontal plane above the level of the work support, and overhanging the longitudinal side edges of the latter, reversible motor-actuated means for effecting relative movement between the carriage and work support in the longitudinal direction of the workpiece on the support, a boom carriage slidable in a fore and aft direction on said rods and disposed above the level thereof, reversible motor-actuated means for selectively effecting sliding movements of the boom carriage on said rods, a turret mounted on said boom carriage above the level thereof for rotation about a vertical axis, reversible motor-actuated means mounted on the boom carriage for selectively effecting rotational movements of the turret in either direction throughout an angle of approximately 90 a boom housing pivotally mounted on the turret for fore and aft rocking movements about a horizontal axis, reversible motor-actuated means extending between the boom carriage and boom housing for rocking the latter, a boom rigidly supported on the boom housing and projecting outwardly a slight distance therefrom, a grinding wheel rotatably mounted on the outer end of the boom in work piece traversing relationship, a drive motor fixedly mounted on the boom housing and operatively connected to the grinding wheel in driving relationship, the length of said boom being such that the grinding wheel assumes a position in sufficiently close proximity to the vertical axis of rotation of the turret that it is constrained at all times to traverse the workpiece at a region which lies between the vertical planes of said widely spaced parallel guide rods, and control means for selectively actuating said reversible motor-actuated means individually and in unison.

2. In a conditioning machine, the-combination set forth in claim 1 and wherein said reversible motor-actuated means for effecting rocking movements of the boom housing includes an extensible and contractible hydrauliccylinder and plunger assembly connected at one end to a fixed point on the boomcarriage adjacent the rear end thereof and at the other end to the boom housing at a point adjacent to the rear end of the latter.

3. In a machine for conditioning the surface of an elongated workpiece such as a slab, incombination, a fixed support for the workpiece, track rail structures positioned forwardly and rearwardly of the work support and extending lengthwise thereof, a main carriage adapted to travel on the rear track rail structure,'a tail stock carriage adapted to travel on the forward track rail structure, a pair of overhead widely spaced parallel guide rods completely overlying and extending in a fore and aft direction transversely of the work support, lying in a common horizontal plane above the level of said work support, and overhanging the longitudinal side edges of the latter, said rods having their rear ends secured to the main carriage and their forward ends secured to the'tail stock carriage, individual reversible motor-actuated means for impelling each carriage along its associated track rail structure selectively in opposite directions, a boom carriage slidable in a fore and aft direction on said guide rods and disposed above the level thereof, reversible motor-actuated means for selectively effecting sliding movements of the boom carriage on said guide rods, a turret on said boom carriage above the level thereof for rotation about a vertical axis, reversible motor-actuated means mounted on the boom carriage for selectively effecting rotational movements of the turret in either direction throughout an angle of approximately a boom housing pivotally mounted on the turret for fore and aft rocking movements about a horizontal axis, reversible'motoractuated means extending between the boom carriage and boom housing for rocking the latter, a boom rigidly supported on one end of the boom housing and project; ing outwardly a slight distance therefrom, a grinding wheel rotatably mounted on the outer end of the boom in workpiece traversing relationship, and an electric drive motor mounted on the boom housing at the other end thereof in counter-balancing relationship with respect to the boom, and means operatively connecting said drive motor to the grinding wheel in driving relationship, the length of said boom being such that the grinding wheel assumes a position in sufficiently close proximity to the vertical axis of rotation of the turret that it is constrained at all times to traverse the workpiece at a region which lies between the vertical planes of said widely spaced parallel guide rods, and control means for selectively actuating said reversible motoractu ated means individually and in unison.

4. In a conditioning machine, the combination set forth in claim 3 and wherein the reversible motor-actuated means for effecting sliding movements of the boom carriage on said guide rods comprises a cylinder positioned in close proximity to each guide rod and having one end thereof secured to the main carriage and the other end secured to the tail stock carriage, a piston slidable in said cylinder, a cable seal effectively closing each end of the cylinder, a pair of cable sections secured to the opposite sides of the piston and passing outwardly of the opposite ends of the cylinder and through said cable seals, a pulley for each cable section, one pulley being mounted on the main carriage and the other pulley being mounted on the tail stock carriage, said cable sections passing around said pulleys and secured to the boom carriage, an hydraulic pump mounted on the main carriage and operatively connected to the opposite ends of each of said cylinders, means for reversing the flow of hydraulic fluid from said hydraulic pump to said cylinders, and means connecting said pump to said electric motor.

5; In a conditioning machine, the combination set forth in claim 3 and wherein said reversible motor-actuated means for effecting rotational movements of the turret comprises a reversible rotary hydraulic motor operatively connected to the turret in driving relationship, an hydraulic pump on said main carriage, flexible hydraulic connections between said pump and rotary motor, and means for reversing the flow of hydraulic fluid from said pump to said rotary motor.

6. A conditioning machine as set forth in claim 3 and wherein the reversible motor-actuated means for impelling the main carriage along its associated track rails includes a first hydraulic motor operatively connected in driving relationship to such carriage, the reversible motor-actuated means for impelling the tail stock carriage along its associated track rail includes a second hydraulic motor operatively connected in driving relationship to such carriage, the reversible motor-actuated means for effecting sliding movements of the boom carriage includes a'third hydraulic motor operatively connected in driving relationship thereto, the reversible motor-actuated means for effecting rotational movements of the turret includes a fourth hydraulic motorand operatively' connected thereto in driving relationship, said pumps and electric drive motor being mounted on the main carriage.

7. A conditioning machine as setforth in claim 3 and including, additionally, an operators cab mounted on the boom carriage in close proximity to, said boom, substantially at the horizontal level of the boom housing and between said widely spaced parallel guide rods,

said cab being movable bodily with the boom carriage, said cab being provided with operating controls for selectively reversing the flow of actuating fluid from each pump to its'associated hydraulic motors. 

1. In a machine for conditioning the upper surface of an elongated workpiece such as a slab, in combination, a work support for the workpiece, a main carriage, a pair of widely spaced overhead parallel guide rods mounted on said main carriage and completely overlying and extending in a fore and aft direction transversely of the work support, lying in a common horizontal plane above the level of the work support, and overhanging the longitudinal side edges of the latter, reversible motor-actuated means for effecting relative movement between the carriage and work support in the longitudinal direction of the workpiece on the support, a boom carriage slidable in a fore and aft direction on said rods and disposed above the level thereof, reversible motor-actuated means for selectively effecting sliding movements of the boom carriage on said rods, a turret mounted on said boom carriage above the level thereof for rotation about a vertical axis, reversible motor-actuated means mounted on the boom carriage for selectively effecting rotational movements of the turret in either direction throughout an angle of approximately 90* a boom housing pivotally mounted on the turret for fore and aft rocking movements about a horizontal axis, reversible motor-actuated means extending between the boom carriage and boom housing for rocking the latter, a boom rigidly supported on the boom housing and projecting outwardly a slight distance therefrom, a grinding wheel rotatably mounted on the outer end of the boom in work piece traversing relationship, a drive motor fixedly mounted on the boom housing And operatively connected to the grinding wheel in driving relationship, the length of said boom being such that the grinding wheel assumes a position in sufficiently close proximity to the vertical axis of rotation of the turret that it is constrained at all times to traverse the workpiece at a region which lies between the vertical planes of said widely spaced parallel guide rods, and control means for selectively actuating said reversible motoractuated means individually and in unison.
 2. In a conditioning machine, the combination set forth in claim 1 and wherein said reversible motor-actuated means for effecting rocking movements of the boom housing includes an extensible and contractible hydraulic cylinder and plunger assembly connected at one end to a fixed point on the boom carriage adjacent the rear end thereof and at the other end to the boom housing at a point adjacent to the rear end of the latter.
 3. In a machine for conditioning the surface of an elongated workpiece such as a slab, in combination, a fixed support for the workpiece, track rail structures positioned forwardly and rearwardly of the work support and extending lengthwise thereof, a main carriage adapted to travel on the rear track rail structure, a tail stock carriage adapted to travel on the forward track rail structure, a pair of overhead widely spaced parallel guide rods completely overlying and extending in a fore and aft direction transversely of the work support, lying in a common horizontal plane above the level of said work support, and overhanging the longitudinal side edges of the latter, said rods having their rear ends secured to the main carriage and their forward ends secured to the tail stock carriage, individual reversible motor-actuated means for impelling each carriage along its associated track rail structure selectively in opposite directions, a boom carriage slidable in a fore and aft direction on said guide rods and disposed above the level thereof, reversible motor-actuated means for selectively effecting sliding movements of the boom carriage on said guide rods, a turret on said boom carriage above the level thereof for rotation about a vertical axis, reversible motor-actuated means mounted on the boom carriage for selectively effecting rotational movements of the turret in either direction throughout an angle of approximately 90*, a boom housing pivotally mounted on the turret for fore and aft rocking movements about a horizontal axis, reversible motor-actuated means extending between the boom carriage and boom housing for rocking the latter, a boom rigidly supported on one end of the boom housing and projecting outwardly a slight distance therefrom, a grinding wheel rotatably mounted on the outer end of the boom in workpiece traversing relationship, and an electric drive motor mounted on the boom housing at the other end thereof in counterbalancing relationship with respect to the boom, and means operatively connecting said drive motor to the grinding wheel in driving relationship, the length of said boom being such that the grinding wheel assumes a position in sufficiently close proximity to the vertical axis of rotation of the turret that it is constrained at all times to traverse the workpiece at a region which lies between the vertical planes of said widely spaced parallel guide rods, and control means for selectively actuating said reversible motor-actuated means individually and in unison.
 4. In a conditioning machine, the combination set forth in claim 3 and wherein the reversible motor-actuated means for effecting sliding movements of the boom carriage on said guide rods comprises a cylinder positioned in close proximity to each guide rod and having one end thereof secured to the main carriage and the other end secured to the tail stock carriage, a piston slidable in said cylinder, a cable seal effectively closing each end of the cylinder, a pair of cable sections secured to the opposite sides of the piston and passing outwardly of the opposite endS of the cylinder and through said cable seals, a pulley for each cable section, one pulley being mounted on the main carriage and the other pulley being mounted on the tail stock carriage, said cable sections passing around said pulleys and secured to the boom carriage, an hydraulic pump mounted on the main carriage and operatively connected to the opposite ends of each of said cylinders, means for reversing the flow of hydraulic fluid from said hydraulic pump to said cylinders, and means connecting said pump to said electric motor.
 5. In a conditioning machine, the combination set forth in claim 3 and wherein said reversible motor-actuated means for effecting rotational movements of the turret comprises a reversible rotary hydraulic motor operatively connected to the turret in driving relationship, an hydraulic pump on said main carriage, flexible hydraulic connections between said pump and rotary motor, and means for reversing the flow of hydraulic fluid from said pump to said rotary motor.
 6. A conditioning machine as set forth in claim 3 and wherein the reversible motor-actuated means for impelling the main carriage along its associated track rails includes a first hydraulic motor operatively connected in driving relationship to such carriage, the reversible motor-actuated means for impelling the tail stock carriage along its associated track rail includes a second hydraulic motor operatively connected in driving relationship to such carriage, the reversible motor-actuated means for effecting sliding movements of the boom carriage includes a third hydraulic motor operatively connected in driving relationship thereto, the reversible motor-actuated means for effecting rotational movements of the turret includes a fourth hydraulic motor operatively connected in driving relationship thereto, the reversible motor-actuated means for rocking the boom housing includes a fifth hydraulic motor operatively connected in driving relationship thereto, the conditioning machine further including a first pump for supplying actuating fluid to said first and second hydraulic motors, a second pump for supplying actuating fluid to said second, third, fourth and fifth hydraulic motors, and an electric motor common to said pumps and operatively connected thereto in driving relationship, said pumps and electric drive motor being mounted on the main carriage.
 7. A conditioning machine as set forth in claim 3 and including, additionally, an operator''s cab mounted on the boom carriage in close proximity to said boom, substantially at the horizontal level of the boom housing and between said widely spaced parallel guide rods, said cab being movable bodily with the boom carriage, said cab being provided with operating controls for selectively reversing the flow of actuating fluid from each pump to its associated hydraulic motors. 